diff --git a/js/src/ds/LifoAlloc.h b/js/src/ds/LifoAlloc.h
index 807313c2af30..8e3b45fea554 100644
--- a/js/src/ds/LifoAlloc.h
+++ b/js/src/ds/LifoAlloc.h
@@ -11,6 +11,11 @@
 #include "mozilla/Attributes.h"
 #include "mozilla/DebugOnly.h"
 #include "mozilla/GuardObjects.h"
+#include "mozilla/ASan.h"
+
+#if defined(MOZ_VALGRIND)
+#include "valgrind/memcheck.h"
+#endif
 
 /*
  * This data structure supports stacky LIFO allocation (mark/release and
@@ -66,7 +71,9 @@ class BumpChunk
     void setBump(void *ptr) {
         JS_ASSERT(bumpBase() <= ptr);
         JS_ASSERT(ptr <= limit);
-        mozilla::DebugOnly<char *> prevBump = bump;
+#if defined(DEBUG) || defined(MOZ_ASAN) || defined(MOZ_VALGRIND)
+        char* prevBump = bump;
+#endif
         bump = static_cast<char *>(ptr);
 #ifdef DEBUG
         JS_ASSERT(contains(prevBump));
@@ -75,6 +82,19 @@ class BumpChunk
         if (prevBump > bump)
             memset(bump, 0xcd, prevBump - bump);
 #endif
+
+        /* Poison/Unpoison memory that we just free'd/allocated */
+#if defined(MOZ_ASAN)
+        if (prevBump > bump)
+            ASAN_POISON_MEMORY_REGION(bump, prevBump - bump);
+        else if (bump > prevBump)
+            ASAN_UNPOISON_MEMORY_REGION(prevBump, bump - prevBump);
+#elif defined(MOZ_VALGRIND)
+        if (prevBump > bump)
+            VALGRIND_MAKE_MEM_NOACCESS(bump, prevBump - bump);
+        else if (bump > prevBump)
+            VALGRIND_MAKE_MEM_UNDEFINED(prevBump, bump - prevBump);
+#endif
     }
 
   public:
diff --git a/layout/base/nsPresArena.cpp b/layout/base/nsPresArena.cpp
index 1bbbca8d057f..8721eecbc398 100644
--- a/layout/base/nsPresArena.cpp
+++ b/layout/base/nsPresArena.cpp
@@ -24,21 +24,9 @@
 #endif
 
 #include "mozilla/StandardInteger.h"
+#include "mozilla/ASan.h"
 
-#if defined(MOZ_ASAN)
-// XXX These come from sanitizer/asan_interface.h but that header doesn't seem
-// to be installed by default?
-extern "C" {
-  void __asan_poison_memory_region(void const volatile *addr, size_t size)
-    __attribute__((visibility("default")));
-  void __asan_unpoison_memory_region(void const volatile *addr, size_t size)
-    __attribute__((visibility("default")));
-#define ASAN_POISON_MEMORY_REGION(addr, size)   \
-  __asan_poison_memory_region((addr), (size))
-#define ASAN_UNPOISON_MEMORY_REGION(addr, size) \
-  __asan_unpoison_memory_region((addr), (size))
-}
-#elif defined(MOZ_VALGRIND)
+#if defined(MOZ_VALGRIND)
 #include "valgrind/memcheck.h"
 #endif
 
diff --git a/mfbt/ASan.h b/mfbt/ASan.h
new file mode 100644
index 000000000000..fd728d7bb8cd
--- /dev/null
+++ b/mfbt/ASan.h
@@ -0,0 +1,27 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Provides ASan (AddressSanitizer) specific functions that are normally
+ * provided through the sanitizer/asan_interface.h header installed by ASan.
+ */
+
+#ifndef mozilla_ASan_h_
+#define mozilla_ASan_h_
+
+#ifdef MOZ_ASAN
+extern "C" {
+  void __asan_poison_memory_region(void const volatile *addr, size_t size)
+    __attribute__((visibility("default")));
+  void __asan_unpoison_memory_region(void const volatile *addr, size_t size)
+    __attribute__((visibility("default")));
+#define ASAN_POISON_MEMORY_REGION(addr, size)   \
+  __asan_poison_memory_region((addr), (size))
+#define ASAN_UNPOISON_MEMORY_REGION(addr, size) \
+  __asan_unpoison_memory_region((addr), (size))
+}
+#endif
+
+#endif  /* mozilla_ASan_h_ */
diff --git a/mfbt/exported_headers.mk b/mfbt/exported_headers.mk
index ffd3405a5c50..2357c9c6121f 100644
--- a/mfbt/exported_headers.mk
+++ b/mfbt/exported_headers.mk
@@ -9,6 +9,7 @@
 EXPORTS_NAMESPACES += mozilla
 
 EXPORTS_mozilla += \
+  ASan.h \
   Assertions.h \
   Attributes.h \
   BloomFilter.h \